To enzymatically synthesize vitamin D derivatives, we screened about 300 Streptomyces sp. strains. Streptomyces sclerotialus FERM BP-1370 and Streptomyces roseosporus FERM BP-1574 were found to have the ability to convert 25-hydroxyvitamin D3 and la-hydroxyvitamin D3, respectively, to la,25-dihydroxyvitamin D3. The average rates of lo hydroxylation of 25-hydroxyvitamin D3 were 6.9 ,ug literminwith FERM BP-1370 and 7.0 ,ug liter-1 min-' with FERM BP-1574. The specific cytochrome P-450 inhibitors carbon monoxide, SKF-525-A, and metyrapone inhibited the hydroxylation of la-and 25-hydroxyvitamin D3 to la,25-dihydroxyvitamin D3 by FERM BP-1370 and FERM BP-1574. The cytochromes P-450 of these strains were detected by reduced CO difference spectra in the whole-cell suspensions. The appearance of cytochrome P-450 suggests that the cytochromes P-450 of FERM BP-1370 and FERM BP-1574 carry out the hydroxylation of 25-and la-hydroxyvitamin D3 to la,25-dihydroxyvitamin D3.

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During our screening program of natural products from fungal metabolites for drugs effective against tumor cell lines, we discovered a new isopatulin derivative, pintulin, from the fermentation broth oi Penicillium vulpinum F-4148. Pintulin shows weak activity against tumor cell lines, compared to that of adriamycin.In the course of our screening program for low molecular weight antitumor compoundsamongfungal metabolites using HL-60 cells, we have discovered a new cytocidal compoundpintulin from the culture broth of Penicillium vulpinum F-4148. Pintulin, the structure of which was determined by spectral analysis as shown in Fig. 1, is a derivative of isopatulin1^The present paper describes the taxonomy and fermentation of the producing organism and the isolation, physico-chemical properties, structure and biological activities of pintulin. Results and Discussion TaxonomyThe strain F-4148 was isolated from a soil sample collected at Towada city, Aomori prefecture in Japan. The strain F-4148 grew well on such agar media as potato-glucose agar, Czapek-Dox agar, and YpSs agar. The morphological observations of the colonies formed on potato-glucose agar for 7 days at 25°C were performed under a light microscope.The results were summarized in Table 1 and irregularly to the outside on the apical areas of a bundle of coremia, where 1~5 of phialides were verticillate. The phialide was cylindrical with a size of 6.01 7.5/mi x 2.0~3.0/mi and formed phialoconidia like a chain from a slightly thin tip. Conidia was greenish gray and smooth on the surface, and the feature was globose to subglobose, slightly slender in a part and plane. The size ofconidia was 3.0~5.8 /mi x 3.0~4.2/mi. The strain 4148 could grow at the range of6 to 29°C in SABROUD

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